1. Field of the Invention
The invention relates to a method and a device for operating a particle sensor arranged in an exhaust duct of an internal combustion engine of a motor vehicle having a sensor support. At least two sensor electrodes are arranged on one side of the sensor support and are exposed to an exhaust-gas flow in the exhaust duct.
2. Description of the Related Art
Ever more stringent legal regulations with regard to admissible pollutant emissions of motor vehicles with internal combustion engines make it necessary to keep pollutant emissions during the operation of the internal combustion engine as low as possible. This may firstly be realized by a reduction in the pollutant emissions generated during the combustion of the air/fuel mixture in respective cylinders of the internal combustion engine. Secondly, use is also made of exhaust-gas aftertreatment systems. In the case of diesel engines, exhaust-gas recirculation is one of the most important measures for lowering nitrogen oxide emissions. Soot particle sensors are primarily provided for monitoring soot particle filters. In conjunction with exhaust-gas recirculation, it may nevertheless be advantageous to measure a soot particle concentration of the exhaust gas at other locations in an exhaust tract of the internal combustion engine, for example upstream of the soot particle filter.
DE 10 2007 060 939 A1 discloses a method for operating a particle sensor for determining a particle content in a gas flow, wherein the particle sensor is constructed from at least one electrically insulating support and from at least two electrodes affixed to said support, and wherein, within a measurement interval between two regeneration phases of the particle sensor, a change in resistance and/or a change in impedance between the electrodes is evaluated to determine the particle content. During a measurement interval, the particle sensor is operated in accumulation phases and in measurement phases in cyclic alternation, and that different voltages and/or voltage waveforms are applied to the electrodes during the accumulation phases and the measurement phases.